A common peony, Paeonia officinalis 'Plena'. The oldest plant in the garden. The original plant is over 200 years old.
Ants are common on peony buds before they open due to the sweet nectar there.
Jerry
As usual these pics are just super. I've just spent 30 min going through a stack of your pics and havent even finish half of them.
Good Luck
Lowell